maurizio,
As I know nothing of Delphi, I can't help you with that, but in a class in a
VB DLL, I'd do something like:

'**<clsMyXL.cls
Private MyXLApp As Object

Property Set SetXLInstance(vData As Object)
Set MyXLApp = vData
'Do some checking to make it is an Excel.Application object
End Property

Public Function ManipulateXL(argNewCaption As String) As Long
If MyXLApp Is Nothing Then Exit Function
With MyXLApp
.Caption=argNewCaption
'Or whatever you need to do
End With
End Function

Private Sub Class_Initialize()
'Any code you need
End Sub

Private Sub Class_Terminate()
'release the reference
Set MyXLApp = Nothing
End Sub
'**</clsMyXL.cls

And calling this from VBA:
Dim MyDelphiClass=MyDelphiDLL.clsMyXL
Set MyDelphiClass=New MyDelphiDLL.clsMyXL
With MyDelphiClass
Set .SetXLInstance=Excel.Apllication
.ManipulateXL "New Caption"
End With
'etc........

NickHK

"maurizio" wrote in message
oups.com...
1) Delphi can use Excel as a server with early binding (binding Excel's
type library),
but this adds about 350 kb to its code: i don't like it.

2) My DLL is, mostly, a library of functions that are called from VBA.
However, having
the right reference, the DLL can interact with and/or transfer data to
Excel directly.
Further, it would be nice to move part of the code from VBA to the DLL
(maybe
not faster, but at least to protect the code).

3) For Delphi, the reference to Excel is simply a variant (to be
precise an OleVariant,
i.e. a variant compatible with ole types). You create it, for example,
with the usual

xlapp := GetObject ('Excel.Application');

(well, in Delphi the method is called GetActiveOleObject )

4) Delphi knows how to treat xlapp as a IDispatch interface, so it
accepts a
statement like

xlapp.Caption := 'My application';

which is identical to a vba statement.

The whole point was only related to the inconvenience of the GetObject
method:
assuming we have multiple copies of Excel running at the same time, how
do you make yourself sure that you're are linking your dll to the RIGHT
instance ?

My idea was to pass to the dll (in an initialization step) the object
Excel.Application:
after all this should be passed somehow as an address, from which it
should be
possible to recover the right value to initialize the xlapp variable in
Delphi.

Hope this makes a little bit more clear the original post and its
purpose.